The invention relates to apparatus and process of forming convolutions in a TEFLON or thermoplastic tubing by use of a helical mandrel and a system of gears, each gear thereof having surface areas that are complemental to the helix so that a tube which is passed through the device is emitted or extruded as a corrugated member.
An example of the earlier concept of winding a wire on a threaded mandrel for deforming a tubular member is disclosed by U.S. Pat. No. 3,635,255 to Kramer. The patent to Roberts et al, U.S. Pat. No. 3,021,245 also discloses a mandrel that is shaped to resemble a helix. In these devices, a tubular member was placed over the mandrel and a wire was wound about the mandrel, deforming the tubular member in a convoluted and corrugated manner. The wire was removed from the outside of the tubular member and scraped. The convoluted/corrugated tubular member was then removed from the mandrel.